1. Field of the Invention
The present invention relates to a printing apparatus, such as an ink jet printer and an ink jet plotter, and also to an ink cartridge detachably attached to a printer main body of the printing apparatus. More specifically the invention pertains to a technique of processing and storing required pieces of information in the ink cartridge.
2. Description of the Related Art
The printing apparatus like the ink jet printer and the ink jet plotter mainly includes an ink cartridge, in which one or plural inks are kept, and a printer main body with a print head to carry out actual printing operations on a printing medium. The print head ejects ink fed from the ink cartridge onto the printing medium, such as printing paper, so as to implement printing on the printing medium. The ink cartridge is designed to be detachably attached to the printer main body. A new ink cartridge has a predetermined quantity of ink kept therein. When the ink kept in an ink cartridge runs out, the ink cartridge is replaced with a new one. Such a printing apparatus is arranged to cause the printer main body to calculate the remaining quantity of ink in the ink cartridge based on the amount of ink transferred from the print head and to inform the user of a state of running out of the ink, in order to prevent the printing procedure from being interrupted by the out-of-ink.
The data on the remaining quantities of inks are generally stored only in the printer main body or in a printer driver that controls the printer. In the event that a first ink cartridge is replaced with a second ink cartridge in the course of the printing operation, the information relating to the first ink cartridge, such as the data on the remaining quantities of inks, are thus lost or made wrong.
One proposed technique to solve this problem utilizes a non-volatile memory provided in the ink cartridge and causes the required data, for example, the data on the remaining quantities of inks, to be written from the printer main body into the non-volatile memory (for example, JAPANESE PATENT LAID-OPEN GAZETTE No. 62-184856). In the case of replacement of the ink cartridge during the printing operation, this technique ensures the storage of the data on the remaining quantities of inks.
The data on the remaining quantities of inks is required to have a relatively high accuracy, in order to inform the user of the precise timing of replacement of the ink cartridge. Storage of such data with a high accuracy in the ink cartridge makes the required storage capacity undesirably large. In the case where the data on the remaining quantities of inks has only a low accuracy, on the other hand, the timing of an alarm of the ink end state, in which a certain ink in the ink cartridge is running out, may significantly be contradictory to the actual remaining quantity of ink. In a structure that updates the data on the remaining quantities of inks at a power-off time, the printer main body reads the data on the remaining quantity of each ink from the ink cartridge at every start of power supply and interprets the read-out data as a value of the lower limit within the preset accuracy. By way of example, it is assumed that the data stored in the ink cartridge expresses the remaining quantity of each ink as a value of percentage in the range of 0 to 100% and has a length of 1 byte (8 bits) and an accuracy of 1%. When the data read from the ink cartridge is xe2x80x9850xe2x80x99, the printer main body can not specify the exact value of the data. The data xe2x80x9850xe2x80x99 may be obtained by rounding 50.9 or 50.1. In order to prepare for the worst, the printer main body deals with the data xe2x80x9850xe2x80x99 as a value of the lower limit xe2x80x9850.0xe2x80x99.
In this structure, even in the case where only a little quantity of ink is used, data should be reduced by 1%. This means that repeating such use 100 times causes the data on the remaining quantity of ink in the ink cartridge to be equal to 0, although there is still a sufficient quantity of ink remaining in the ink cartridge. In another structure that does not reduce data by 1% in the case of use of a little quantity of ink, repeating such use many times causes an alarm of the ink end state not to be given even if the actual remaining quantity of ink is equal to zero. In an ink cartridge with a memory or a printer using such an ink cartridge, the storage capacity of several bytes for each ink is required to monitor the remaining quantity of ink precisely. In the case of a color ink cartridge that keeps a plurality of different color inks in a casing thereof, a certain storage capacity should be allocated to each color ink. For example, in the case of a color ink cartridge including five color inks, if the required storage capacity for each color ink is 4 bytes, the total storage capacity is as large as 5xc3x974=20 bytes (20xc3x978=160 bits).
Increasing the data length to be written makes it difficult to write all the required data within a short time period after a power-off operation. When a power switch mounted on a switch panel of the printer is operated, the applicable sequence enables the printer to confirm conclusion of the writing operation of data into the memory of the ink cartridge, before actually turning the power source off. In the case where the power supply is forcibly cut off on the side of the power line by pulling the power plug out of the socket or turning off the power of an extension connected to a computer, however, the writing operation of data into the memory of the ink cartridge should be completed within a very short time period. If the power voltage is lost in the course of the writing operation, the reliability of data in the ink cartridge is significantly lowered. This prevents the ink cartridge from being used adequately. The use of the memory having a large storage capacity undesirably increases the manufacturing cost of expendable ink cartridges. This is also undesirable from the viewpoint of resource saving.
The problems discussed above arise in any printing apparatus that does not directly measure the remaining quantity of ink or the amount of ink consumption in an ink cartridge but causes the printer to compute such data, and in an ink cartridge attached thereto. Such printing apparatus includes an ink jet-type printing apparatus that uses ink obtained by mixing or dissolving a pigment or a dye with or in a solvent and ejects ink droplets in the liquid state to implement printing, a printing apparatus that uses an ink cartridge with an ink toner accommodated therein, and a thermal transfer-type printing apparatus.
The object of the present invention is thus to provide a technique that is applicable to a printer and a cartridge attached thereto and enables information relating to the cartridge, such as pieces of information on remaining quantities of inks, to be adequately processed, while not increasing the manufacturing cost of the cartridge.
At least part of the above and the other related objects is actualized by a printer, to which a cartridge is detachably attached, wherein the cartridge keeps ink therein and has a rewritable non-volatile memory. The printer causes the ink kept in the ink cartridge to be transferred from a print head mounted on the printer to a printing medium, thereby implementing a printing operation. The printer includes: a rewritable printer memory; an information writing unit that writes information on a quantity of ink in the ink cartridge, which is consumed with a progress of a printing operation on the printing medium, as data of a predetermined number of bits, into the printer memory; and a memory writing unit that converts the information on the quantity of ink in the ink cartridge to data of a specific number of bits, which is less than the predetermined number of bits, and writes the converted data of the specific number of bits into the non-volatile memory included in the cartridge.
The printer of the present invention writes the information on the quantity of ink in the cartridge, which is consumed with a progress of a printing operation on the printing medium, as data of a predetermined number of bits into the printer memory and as converted data of a specific number of bits, which is less than the predetermined number of bits, into the non-volatile memory of the cartridge. This arrangement effectively prevents an undesirable increase of the storage capacity, while enabling the information on the quantity of ink to be stored in a non-volatile manner in the ink cartridge.
The technique applicable to reduce the number of bits may omit lower bits from the data of the predetermined number of bits written in the printer memory, or alternatively may convert the data of the predetermined number of bits written in the printer memory to data representing a percentage.
In accordance with one preferable application of the present invention, the applicable technique determines whether or not the information on the quantity of ink written in the printer memory is coincident with the converted data of the specific number of bits written in the non-volatile memory at a time of a start of power supply. The technique applies the data of the predetermined number of bits stored in the printer memory for subsequent processing with regard to the quantity of in the cartridge, when it is determined that the information on the quantity of ink is coincident with the converted data of the specific number of bits. This arrangement enables the subsequent processing with regard to the quantity of ink to be carried out, based on the data of the greater number of bits stored in the printer memory, that is, the data with a higher accuracy, as long as the cartridge is not replaced with another.
In accordance with another preferable application of the present invention, the applicable technique determines whether or not the information on the quantity of ink written in the printer memory is coincident with the converted data of the specific number of bits written in the non-volatile memory at a time of a start of power supply. The technique re-converts the data of the specific number of bits written in the non-volatile memory into the data of the predetermined number of bits, writes the re-converted data of the predetermined number of bits as the information on the quantity of ink into the printer memory, and applies the re-converted data of the predetermined number of bits for subsequent processing with regard to the quantity of ink in the cartridge, when it is determined that the information on the quantity of ink is not coincident with the converted data of the specific number of bits. In this case, the subsequent processing with regard to the quantity of ink is carried out, based on the data on the quantity of ink stored in the non-volatile memory of the cartridge.
In accordance with still another preferable application of the present invention, aL piece of identification information that enables identification of the cartridge, is stored in the non-volatile memory of the cartridge. The applicable technique here reads the piece of identification information stored in the non-volatile memory at a time of a start of power supply and/or at a time of a replacement of the cartridge, and stores the read-out piece of identification information. The technique compares the read-out piece of identification information with the stored piece of identification information, which has been read out previously, so as to determine coincidence or non-coincidence thereof. The technique applies the data of the predetermined number of bits stored in the printer memory for subsequent processing with regard to the quantity of ink in the cartridge, when it is determined that the read-out piece of identification information is coincident with the stored piece of identification information. In this configuration, the cartridge is identified accurately using the identification information of the cartridge. This arrangement enables the subsequent processing with regard to the quantity of ink to be carried out, based on the data of the greater number of bits stored in the printer memory.
In the above structure, the applicable technique compares the read-out piece of identification information with the stored piece of identification information, which has been read out previously, so as to determine coincidence or non-coincidence thereof. The technique re-converts the data of the specific number of bits written in the non-volatile memory into the data of the predetermined number of bits, writes the re-converted data of the predetermined number of bits as the information on the quantity of ink into the printer memory, and applies the re-converted data of the predetermined number of bits for subsequent processing with regard to the quantity of in the cartridge, when it is determined that the read-out piece of identification information is not coincident with the stored piece of identification information. In this case, the subsequent processing with regard to the quantity of ink is carried out, based on the data on the quantity of ink stored in the non-volatile memory of the cartridge.
It is preferable that not only the information on the quantity of ink with regard to the cartridge currently attached to the printer but the same information with regard to all the cartridges that have been attached to the printer at least once is stored in the printer memory. In this configuration, a piece of identification information that enables identification of the cartridge is stored in the non-volatile memory of the cartridge. The piece of identification information stored in the non-volatile memory is read at a time of a start of power supply and/or at a time of a replacement of the cartridge. By utilizing the read-out piece of identification information, the information on the quantity of with regard to each cartridge having a different piece of identification information is stored into the printer memory. In the case of a replacement of the cartridge, the applicable technique retrieves data stored in the printer memory by utilizing the piece of identification information read from the non-volatile memory, so as to determine whether or not an identical piece of identification information, which is identical with the read-out piece of identification information and represents an identical cartridge, is present in the printer memory. When it is determined that the identical piece of identification information is present in the printer memory, the technique applies the information on the quantity of ink corresponding to the identical piece of identification information for subsequent processing with regard to the quantity of ink in the cartridge. This arrangement enables the processing with regard to the quantity of ink to be carried out with high accuracy even when a plurality of cartridges are successively attached to the printer and used for printing.
In accordance with one application of this structure, when it is determined that the identical piece of identification information is present in the printer memory, the applicable technique determines whether or not the information on the quantity of ink, which corresponds to the identical piece of identification information and is written in the printer memory, is coincident with the converted data of the specific number of bits written in the non-volatile memory. The technique applies the data of the predetermined number of bits, which corresponds to the identical piece of identification information and is stored in the printer memory, for subsequent processing with regard to the quantity of ink in the cartridge, when it is determined that the information on the quantity of ink is coincident with the converted data of the specific number of bits. The structure of this application determines the coincidence with regard to the information on the quantity of ink as well as with regard to the piece of identification information. This arrangement enables the accurate piece of information to be extracted and used as the information on the quantity of ink with regard to the cartridge currently attached to the printer.
In accordance with another application of this structure, when it is determined that the information on the quantity of ink, which corresponds to the identical piece of identification information and is written in the printer memory, is not coincident with the converted data of the specific number of bits written in the non-volatile memory, the applicable technique re-converts the data of the specific number of bits written in the non-volatile memory into the data of the predetermined number of bits, writes the re-converted data of the predetermined number of bits as the information on the quantity of ink corresponding to the identical piece of identification information into the printer memory, and applies the re-converted data of the predetermined number of bits for subsequent processing with regard to the quantity of ink in the cartridge. In this case, the subsequent processing with regard to the quantity of ink is carried out, based on the data on the quantity of ink stored in the non-volatile memory of the cartridge.
In the configuration that carries out the processing with regard to the quantity of ink by taking advantage of the data stored in the two different memories, it is practical that the printer memory has a greater storage capacity than the non-volatile memory included in the cartridge. Incorporating the memory of a large storage capacity in the expendable cartridge is not desirable from both the view points of cost and resource saving.
It is also preferable that the printer memory enables a higher-speed access than the non-volatile memory included in the cartridge. Since the data of the greater number of bits are written into the printer memory, the memory that enables the higher-speed access is desirable.
Data may be written into the non-volatile memory of the cartridge at a variety of timings. For example, the data may be written into the non-volatile memory of the cartridge at a power-off time of the printer and/or at a time of a replacement of the cartridge. This arrangement enables the data stored in the cartridge to be updated when the cartridge is detached from the printer.
The data may be written into the printer memory when a printing operation has been completed with regard to one page and/or with regard to at least one raster line. It is also preferable that the data in the printer memory are updated at a high frequency, whereas data in the non-volatile memory of the cartridge are updated at a lower frequency.
In accordance with one preferable embodiment of the present invention, the printer has a cleaning unit that carries out head cleaning in response to a predetermined operation, wherein the head cleaning causes a preset quantity of ink to be transferred from the print head. In this structure, data are written into the printer memory when the cleaning unit carries out the head cleaning. The ink jet printer may have a cleaning function to prevent nozzles formed on the print head from being clogged. The cleaning operation naturally consumes a certain quantity of ink. It is accordingly preferable to update the information on the quantity of ink after each cleaning operation.
A variety of known memories may be applicable for the non-volatile memory mounted on the cartridge. For example, a memory that transmits data by serial access may be used for the non-volatile memory. This type of memory is generally inexpensive and has a less number of terminals as a chip, which leads to the effect of resource saving, although the storage capacity is relatively small. In this case, data are written into the non-volatile memory in synchronism with a clock for specifying an address.
The clock for specifying the address may be output from a control IC that directly controls a writing operation of data into the non-volatile memory. In this case, the printer memory may be disposed inside the control IC or alternatively outside the control IC.
In one preferable embodiment of the printer, the cartridge is detachably attached to a carriage, which has the print head mounted thereon and moves forward and backward relative to the printing medium. In this case, the printer memory may be mounted on the carriage. In the case where the control IC receives data from a controller of the printer, for example, via communications, it is preferable that the printer memory is located in the vicinity of the control IC. The principle of the present invention is applicable to the structure in which the cartridge is not mounted on the carriage but is set in the printer main body.
The structure of incorporating the non-volatile memory in the cartridge is applicable to any type of the cartridge. For example, in the case where both a black ink cartridge, in which black ink is kept, and a color ink cartridge, in which a plurality of different color inks are kept, are detachably attached to the printer, the non-volatile memory is provided in both the black ink cartridge and the color ink cartridge, and data are written into the respective non-volatile memories. The configuration that provides a non-volatile memory for each cartridge enables the data on the quantity of ink with regard to each cartridge to be processed independently. The principle of the present invention is also applicable to a printer, to which only a black ink cartridge or a color ink cartridge is detachably attached.
The present invention is also directed to a method of managing information in a printer, to which an ink cartridge is detachably attached, wherein the ink cartridge keeps ink therein and has a rewritable non-volatile memory and the printer causes the ink kept in the cartridge to be transferred from a print head mounted on the printer to a printing medium, thereby implementing a printing operation. The method includes the steps of: writing information on a quantity of ink in the ink cartridge, which is consumed with a progress of a printing operation on the printing medium, as data of a predetermined number of bits, into a rewritable printer memory incorporated in a main body of the printer; and converting the information on the quantity of ink in the ink cartridge to data of a specific number of bits, which is less than the predetermined number of bits, and writing the converted data of the specific number of bits into the non-volatile memory included in the ink cartridge.
This method of managing the information on the quantity of ink enables the data of the greater number of bits, that is, the data with a high accuracy, to be stored in the printer memory, without applying an excessive load to the non-volatile memory of the cartridge, which has a smaller storage capacity. This arrangement thus enables the information on the quantity of ink in the cartridge to be managed in an appropriate manner.
The method of the present invention may be actualized by a printer or a computer that is connected to the printer. In the latter case, the principle of the present invention is attained by a computer program products or a recording medium, in which a program executed by the computer is recorded. The present invention is accordingly directed to a computer program products, in which a specific program is recorded in a computer readable recording medium. The specific program is used to manage information in a printer, to which a cartridge is detachably attached, wherein the cartridge keeps ink therein and has a rewritable non-volatile memory and the printer causes the ink kept in the cartridge to be transferred from a print head mounted on the printer to a printing medium, thereby implementing a printing operation. The specific program includes: a first program code that causes a computer to write information on a quantity of ink in the cartridge, which is consumed with a progress of a printing operation on the printing medium, as data of a predetermined number of bits, into a rewritable printer memory incorporated in a main body of the printer; and a second program code that causes the computer to convert the information on the quantity of ink in the cartridge to data of a specific number of bits, which is less than the predetermined number of bits, and write the converted data of the specific number of bits into the non-volatile memory included in the cartridge.
The computer reads the recording medium and executes the program codes of the specific program recorded on the recording medium, thereby actualizing the method of managing information discussed above.
The present invention is further directed to a cartridge that keeps ink therein and has a rewritable non-volatile memory. The cartridge is detachably attached to a printer. Information on a quantity of ink in the cartridge, which is consumed with a progress of a printing operation, is written into the non-volatile memory as data of a specific number of bits, which is less than a predetermined number of bits allocated to data stored in the printer.
In the cartridge of the present invention, the information on the quantity of ink is written into the non-volatile memory of the cartridge as data of a specific number of bits, which is less than a predetermined number of bits allocated to data stored in the printer. This arrangement advantageously reduces the required storage capacity of the non-volatile memory.
In the cartridge of the present invention, it is preferable that the information on the quantity of ink is written into the non-volatile memory at a power-off time of the printer and/or at a time of a replacement of the cartridge. Updating the information on the quantity of information at these timings enables the information regarding the latest quantity of ink to be kept in the non-volatile memory of the cartridge, even when a replacement of the cartridge is required unexpectedly.
An EEPROM or a flash memory may be used for the non-volatile memory of the cartridge. Another available structure backs up the contents in a memory by means of a battery, so as to make the battery non-volatile. A bubble memory or a micro-miniature hard disk may also be applicable for the non-volatile memory.
A memory that transmits data by serial access may be applicable for the non-volatile memory. In this case, the information on the quantity of ink is written into the non-volatile memory in synchronism with a clock for specifying an address. The memory of the serial access type is small-sized and has a less number of terminals, thereby attaining the effect of resource saving.
The data written into the non-volatile memory may be obtained by omitting lower bits from the data of the predetermined number of bits stored in the printer or by converting the data of the predetermined number of bits stored in the printer to data representing a percentage. The only requirement is that the data written into the non-volatile memory should have a smaller number of bits and correspond to the data stored in the printer.
In accordance with one preferable application of the present invention, the cartridge has an ink reservoir, in which a plurality of different inks are kept. The data of the specific number of bits are written with regard to each of the plurality of different inks into the non-volatile memory. This arrangement enables plural pieces of information regarding the quantities of the plurality of different inks to be stored in one non-volatile memory.
In one embodiment of the cartridge with a plurality of different inks kept therein, the ink reservoir is divided into at least three ink chambers, in which at least three different inks are kept, and the non-volatile memory has a plurality of information storage areas, in each of which information on a quantity of each of the at least three different inks is stored independently. A storage capacity of not greater than 2 bytes is allocated respectively to the plurality of information storage areas.
In this structure of the embodiment, the storage capacity of not greater than 2 bytes is allocated to each ink. When the cartridge has three different inks kept therein, the total storage capacity required for storing the information on the quantities of the three different inks is not greater than 6 bytes. In the case where the ink reservoir is divided into five ink chambers, in which five different inks are kept, the total storage capacity required for storing the information on the quantities of the five different inks is not greater than 10 bytes.
In any of the applications of the present invention discussed above, the information on the quantity of ink may be the remaining quantity of or a cumulative amount of ink consumption with regard to the cartridge. The information may otherwise be an amount of ink consumption while the cartridge of interest is attached to the printer. There is a cartridge that can be refilled with ink. The cartridge of this type is detached from the printer, refilled with ink, and attached again to the printer, for example, in response to an instruction of xe2x80x98refillxe2x80x99 displayed on the switch panel. In this case, it is required to monitor the amount of ink consumption while the cartridge is attached to the printer.
These and other objects, features, aspects, and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments with the accompanying drawings.